This disclosure relates to roaming in a communications network.
Mobile Internet protocol (“Mobile IP”) is a communications protocol that defines how mobile devices such as mobile computers maintain transport session continuity and constant reachability over IP-based wireless or wired networks. Mobile IP is specified in a request for comments (RFC) 3220 dated January 2002 as set out by the Mobile IP working group in the Internet engineering task force (IETF).
Mobile IP is based on the notion of a home subnet in which each mobile device may be assigned a “fixed” home-address. The home-address is an invariant IP address that makes it appear that the mobile device is always attached to the home network, independent of its current physical location. If the mobile device roams from the home subnet to a foreign network, it acquires a care-of-address which is notified to the mobile device's home agent through a registration request. This enables the home agent to forward packets destined to the mobile device to the specified care-of address.